Avaliação química, antioxidante, toxicológica e microencapsulação do óleo essencial de Campomanesia adamantium (cambess.) o. berg com aplicação em creme cosmético anti-aging

Abstract

Plants are a valuable source of bioactive substances, driving scientific research into new natural compounds. Brazil has a rich reserve of these natural products as it has the greatest plant diversity on the planet. The Campomanesia adamantium species, endemic to the Cerrado biome, stands out for its bioactive and nutritious compounds, found especially in the fruit, commonly called guavira. The pulp is used for juices and jellies, and the residue generated during pulping, consisting of peel and seed, is a source of essential oil (EO), still little explored.. Due to the volatility and instability of EOs under certain environmental conditions that make their application difficult, microencapsulation can be a promising alternative in several areas. Toxicity analyses of new natural products are necessary, preferably with in vitro and in vivo tests, to verify the safety of its use. So, the objective of the study was to analyze the EO extracted by hydrodistillation of C. adamantium fruit residues concerning its chemical composition, antioxidant capacity, and toxicity profile in vitro and in vivo, as well as its application in free and microencapsulated form in an anti-aging facial cosmetic cream. The EO presented a yield of 0.37% in extraction, with the following constituents as the majority: limonene (18.6%), α-pinene (17.5%), β-ocimene (11.1%) and β-caryophyllene (9.8%). Microcapsules (MC) were obtained by the complex coacervation process followed by freeze-drying, using gelatin 1% (G) and gum arabic 1% (GA) as wall materials, and to optimize the process conditions, a central composite rotational design (CCRD) was applied, totaling 11 formulations. In CCRD, the influence of different G:GA ratios (1:1; 1:2; 1:3; 2:1, and 3:1) and the amount of EO (20% to 42.8%) on the microencapsulation yield, morphology, and antioxidant capacity were evaluated. Formulations F2 and F4 showed better retention of antioxidant capacity (99% and 94%, respectively), adequate morphology, and encapsulation yield of around 68%. Therefore, from the optimization study, with these two formulations, the characterization study was carried out, named MC1 (G:GA 1:2; OE: 40.3%) and MC2 (G:GA 2:1; OE:40.3%). Characterization was carried out regarding chemical composition (gas chromatography/mass spectrometry), EO retention, encapsulation efficiency, morphology, solubility, hygroscopicity, and thermal properties (thermogravimetry and Fourier transform infrared spectroscopy - FTIR) and antioxidant capacity (FRAP and ABTS methods). MC1 and MC2 showed high retention of the same main constituents of the EO, high encapsulation efficiency, and antioxidant capacity similar to the free essential oil. The MC presented an agglomerated form when wet and a slightly porous surface when dry, with a diameter between 12.8 and 76.0 µm. Formulation MC1, due to the greater proportion of GA in relation to G, resulted in MC with a less porous wall, less hygroscopic, and with greater thermal stability than the free essential oil. FTIR analysis indicated the efficiency of wall materials in oil encapsulation. Following the study, EO and MC1 were incorporated (1% and 3%, respectively) in the formulation of an anti-aging cosmetic cream, evaluating organoleptic characteristics (color, odor, appearance, pH), accelerated stability (4 °C, 25 °C, 45 °C), spreadability and microbiological quality. The anti-aging cream maintained a stable emulsion, high spreadability, and organoleptic parameters without changes during 90 days of storage at 25 °C. In the microbiological evaluation, the cream remained in compliance with the legislation. To evaluate toxicity profile, initially the in vitro cytotoxic effects of EO were evaluated against non-tumor cells (PBMC, HDFa, and HaCaT) and tumor cells for melanoma (B16F10-Nex2) using MTT assay. The results showed greater cytotoxicity for the tumor lineage (IC50 = 177.8 μg/ mL) indicating a promising therapeutic potential of EO from guavira residues for the treatment of melanoma. In vivo, the toxicological safety of EO was evaluated against the nematode Caenorhabditis elegans. The EO did not reduce the viability of C. elegans in 24 h and 48 h up to 500 μg/ mL, and did not alter the number of progeny or locomotion, demonstrating toxicological safety at the doses tested. This research was a pioneer in the study of the encapsulation of EO from guavira residue, demonstrated new potential applications, and promoted an innovative approach to safely use this residue. Therefore, the study provides evidence of security of the EO, opening new perspectives for incorporating this oil into cosmetic or therapeutic formulations, in pure or encapsulated form.